FreeCalypso Tango is a compact packaged GSM modem module containing our legendary Calypso chipset inside. These modules were originally made by iWOW Connections Pte Ltd and marketed as iWOW TR-800, but they are now being rebranded as FreeCalypso Tango. Our rebranding of these modules from iWOW TR-800 to FC Tango consists of the following changes:
Our rebranded modules are identified by an official FreeCalypso Tango sticker, as shown in the photo above.
We ship our rebranded modules with FreeCalypso modem firmware in their flash, not iWOW's binary-only firmware.
We have produced significant new documentation for our rebranded modules, correcting iWOW's documentation where it was incorrect and expanding upon it in other places. Our new documentation includes reconstructed schematic design source code (in our ueda language based on the structural subset of Verilog) for the complete internal circuit structure inside the packaged module.
We have two documentation directories on our FTP site that relate to these modules:
Caramel2 is a FreeCalypso development board based around this Tango module.
For complete understanding of the module hardware and how to work with it, we recommend that you read iWOW's TR-800 GSM/GPRS Module Product Technical Specifications document and our FreeCalypso Tango Module Integration Guide.
Between 2013 and 2019, we had several occasions when we really wished that we had a FreeCalypso GSM+GPRS modem module that could compete with mainstream proprietary ones. In the olden days when most civilized countries on Earth still had good working GSM/2G networks and weren't itching to shut them down, there were many packaged modem modules which someone could simply take and incorporate as a component into a larger design such as a smartphone: consider the popular SIM900, SIM800 etc modules. Of course those modules were and are proprietary black boxes — but what if we could have a competing, approximately equivalent packaged module with FreeCalypso inside?
Over the course of those years we did come across some existing historical packaged GSM+GPRS modem modules that had TI Calypso chipset inside: first BenQ M32, then Huawei GTM900. But these modules weren't the answer we were looking for: BenQ M32 used Silabs Aero+ RF transceiver instead of TI Rita, thus the effort to port FreeCalypso firmware to it would have been unreasonable, while GTM900 was just a lousy design, requiring different GTM900-B vs GTM900-P versions for different frequency bands. We had ideas to produce our own FreeCalypso packaged modem module and fit it into a form factor copied from either BenQ or Huawei, but no one ever funded them.
Then at the very end of 2019 we accidentally discovered the existence of iWOW TR-800, a theretofore very obscure GSM+GPRS modem module with TI Calypso chipset inside. Examination of these modules quickly revealed that it is essentially a mass-produced version of TI's Leonardo+ core, approximately corresponding to the core of Leonardo+ rev 5, the version with Epcos D1016 quadband RFFE and a combined flash+RAM MCP. These iWOW modules also served as confirmation that TI's quadband design based on Epcos D1016 really works: we haven't found any other mass-produced Calypso-based phone or modem design that is fully quadband, all others are either single-region 2-band or triband at best, thus we were wondering if perhaps TI's quadband design of Leonardo+ had some flaws. But iWOW TR-800 proved that this quadband RFFE design works perfectly fine, while the reason for the lack of wider adoption of the same was marketing poison.
In light of this new reality that unfolded from 2019 into 2020, we decided that the best course of action was to officially adopt this newly discovered quadband modem module into FreeCalypso family by giving it the new name FreeCalypso Tango and treating it as a bona fida FreeCalypso hardware product. Because our philosophy in FreeCalypso is to stick as close as possible to TI reference designs in both hardware and firmware (in marked contrast to the approach taken by Compal and Chi-Mei in the case of Motorola C1xx, or by BenQ on their M32), and because iWOW TR-800 hardware is really just the core of Leonardo+ factored out into a module, this transformation of TR-800 into FC Tango came about very naturally.
When we officially introduced FreeCalypso Tango as a product in late 2020, the state of GSM/2G services around the world was not yet as dire as it is today (2026). Furthermore, there were some developments less than a year prior to our unveiling of this product that led us to believe that some commercial demand could potentially still exist for such. Therefore, we made preparations for a potential demand, including a streamlined process for converting iWOW TR-800 modules into FC Tango.
However, several more years have passed since then, and absolutely no demand for FC Tango modules occurred — and in the meantime, the availability of GSM/2G cellular network services around the world has become so poor that we now see no conceivable way how anyone would be willing to design in a 2G-specific cellular modem module. As a result of these developments, FC Tango is no longer viewed as an active product, but rather as a historical note.
Because we still have significant stock of iWOW TR-800 modules, we are potentially able to sell them, either as-is or converted to FreeCalypso Tango. However, since there has been absolutely no demand, we do not have any kind of pricing structure in place. Anyone who suddenly becomes interested in these modules should email Mother Mychaela and explain your interest — then we can have a discussion to see if your actual needs and the capabilities of our modules have any match between them.